1. Technical Field
The disclosure generally relates to systems and methods for cleaning the inner surfaces of conveying tubes, piping, or ducts and, more particularly, to systems and methods for cleaning tubes, piping, or ducts using a flexible pig train that engages the inner surfaces of the tubes, piping, or ducts to remove debris. Specifically, one configuration of the system and method uses a pig train that includes a portion formed from the combination of dry ice and glycol.
2. Background Information
Conventional clean-in-place (CIP) systems and methods that are used to clean conveying tubes, pipes, or ducts to a microbiological level require copious amounts of water and chemicals which must be stored, heated to temperatures in excess of 135° F., and pumped through the tubes at a high velocity in order to create the shear forces required to scour the tube walls. The polluted waste water and chemicals then must be discharged to a waste water system for treatment. Conveying tubes used to move food products are cleaned in this manner.
Other clean-in-place systems use a pig as an instrument to flush or purge a piping system. U.S. Pat. No. 6,485,577 discloses a pig and pig launching chamber where the pig is frozen and formed from at least a component of the product stream. Another pig formed from crushed ice is disclosed in U.S. Pat. No. 6,916,383.